Bonding a window into a structure often requires cleaning the window surface where the adhesive is to be applied to remove contaminants, applying a primer to the area of the window to which the adhesive is to be applied, and then applying adhesive generally to the periphery of the window. Thereafter, the window with the adhesive applied thereto is placed into a window frame of the structure with the adhesive disposed between the window frame and the window and the adhesive is cured to hold the window in place. In many embodiments, the window has deposited on its surface, about the periphery, a coating often referred to as an enamel or frit. This coating is typically a black border which is used to prevent degradation of the adhesive by exposure to ultraviolet radiation and is a means of hiding the underlying color trim and adhesives. The enamels are typically ceramic based and require firing temperatures of about 500° C. to 700° C. to cure. In order for the adhesives to bond to such an enamel, a primer is required. The primer is applied to the surface of the ceramic enamel located on the surface of the window. Generally, the ceramic enamel is applied to the glass prior to shaping of the glass. For many windshield applications, the glass needs to be curved. In most operations, the glass is bent to shape after application and firing of the ceramic enamel.
The problem with the present process is that a primer is required to achieve a good durable bond between the adhesive and the enamel located on the glass. Further, the high temperatures necessary to process these ceramic enamels are undesirable. Additionally, an inorganic ceramic coating fused into the glass makes it difficult to recycle the glass, when there is a defect in the glass, which occurs during manufacture of the glass or at the end of life of a vehicle.
One solution to this problem is disclosed in commonly assigned United States Patent Publication number 2006-0287408 to Baikerikar and Mahdi. This reference discloses a composition comprising a) one or more film forming resins having at least one functional group capable of polymerizing; b) one or more reactive diluents capable of reacting with the film forming resin; c) one or more silicon, titanium, zirconium, aluminum, or metal containing compounds capable of promoting adhesion of the composition to glass; d) one or more fillers capable of imparting abrasion resistance to the composition when cured; and e) one or more compounds which is reactive with the film forming resin which also contains an acidic moiety. The coatings prepared from this composition demonstrate excellent abrasion resistance. However, the wet adhesion of these coatings to glass bonding adhesives can be further improved.
What is needed is a coating for glass which can be applied without the need for very, high curing temperatures, which can form a durable bond to glass substrates and to standard adhesives used for bonding glass to structures without the need for pre-application of primers, and which facilitates recycling of the glass.